The underlying goal is to determine the biological role of vanadium in higher animals. The following are more immediate: a. To identify and define all apparent signs of vanadium deficiency in the rat, utilizing a closely controlled environment and a well defined vanadium deficient diet (8-10 ppb vanadium). b. To elucidate the cellular and biochemical changes associated with certain major signs of deficiency. c. To develop the analytical methodology necessary for the determination and monitoring of vandium deficiency in rats with potential application to human studies.